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Modulus-86  build thread
Modulus-86  build thread
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Old 22nd February 2021, 06:27 PM   #5401
jwdevos is offline jwdevos  Netherlands
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Mouser has some stock issues for certain parts as well. Some parts will be in backorder for a few months. For a large order, they give free shipping in batches of availability though so it doesn't bother me too much. If I get impatient I will look for the missing parts at Digi-Key or some other place.
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Old 22nd February 2021, 06:57 PM   #5402
tomchr is offline tomchr  Canada
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You can also just email me for substitutes.

Parts go in/out of stock at Mouser all the time.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 3rd March 2021, 08:55 PM   #5403
kaloyan is offline kaloyan
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Hi guys, I just found this very interesting and loooong tread.

I did not have time to read all postings so if my post duplicates some other posts, please ignore it.
I'm sorry for the long introduction but otherwise would be difficult to get to my point.

INTRODUCTION
There are many well known advantages of the composite topology.
Current sharing (paralleling) approach offers great benefits as well.
That is why combining both sounds very compelling.

Some time ago I built a composite amplifier based on LM1875. Here is a brief summary:
- THD and noise bellow -125dB (the limit of my measuring gadgets) 0.1 to 40W - 2 parallel LM1875 amps
- less then 1mv DC output, usually between 0.2 and 0.5mV.
- no servo
- no Feedback DC decoupling
- stable in wide range of supply voltages (up to +-30V)
- unity gain stable (not good idea though because of the high CM distortion)
- easy to get up to 150W /8ohm combining parallel and bridge 6 LM1875.
- no trace of annoying current limiting feature
Here ends the introduction .

I have built a big number of these amps and the sound quality easily beats many other power amps that I owned during the years, including:
- Hypex UCD 250 equipped with super regulators,
- ICEpower 200AC
- TPA3251 and TPA3255 with air coil output filters (the original boards came from 3e-audio but to get a decent sound I had to mod the output filters and input stage as well)
- different LM3886 and TDA7293 topologies (Not composite amps, for these I'll share me exiting experience some other time).
BUT I did not have the opportunity to compare my amps with the well regarded Modulus-86 power amp,
I'll be very happy to do that!
I live in west LA and if somebody of the community lives in that area and owns modulus-86 amp I'd be very happy to meet and make some critical listening.
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Old Yesterday, 09:06 PM   #5404
jwdevos is offline jwdevos  Netherlands
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Join Date: Dec 2019
Location: Zeeland
Until today, I have ignored SMPS 100% as an option for my amplifiers. Apparently, it was more because of "religious" factors than scientific ones. The design of the Neurochrome preamp power supply got me curious so I did some reading.

Fast forward, I am now considering to power my stereo Modulus-86 build with an SMPS power supply. The design documentation mentions a double Mean Well RPS-200-27-C possibility, without the Mean Well Control module. Is the Mean Well Control module meant for a different setup (a Modulus-686 build maybe)?

I also looked at the SMPS-86 but it seems discontinued (because of competitive/good enough alternatives?). I'm also looking at the Connex SMPS300REh. It seems to fit the requirements nicely: enough power and +/- 30v out of the box. It also has a metal heat sink as a bottom plate which I like, I don't want to introduce a fan in my amplifiers.

Looking at photos of SMPS builds, there are builds with and without a soft start in front of the SMPS. I don't know how to relate SMPS to transformer sizes or whatever, so is a soft start recommended for a 300 watt SMPS?
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Old Yesterday, 10:37 PM   #5405
tomchr is offline tomchr  Canada
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The SMPS-86 was discontinued because it didn't provide enough power to drive the Modulus-86 to clipping with a 4 Ω load. Also, with the Connex SMPS300REh and the Mean Well RPS-series there are better options on the market now.

The Mean Well Control will probably be discontinued. It only works with the RPS/RPP-300/400 series, so not with the 200-series. Also, the Mean Well supplies will power up as soon as they're plugged into the mains voltage, so they can be controlled by an ISS instead.

The Connex SMPS300REh has a built-in soft start, but do note that it still draws quite an inrush current on startup. I had it burn out a 2A rated mains switch during the prototyping of the Modulus-286 Kit (LE). I would use an ISS to control the mains power to it. That also gives you a range of nice features, including a 12 V trigger input, option to use low-voltage switches, dual LED dimmers for ON and STANDBY indication, etc. And soft start, of course.

Tom
__________________
Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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